I was going to fill in my credit card details on the renewal page of the My favourite magazines website when I noticed a warning icon in the url field.
Apparently the site is partially encrypted.

"Parts of the page you are viewing were not encrypted before being transmitted over the internet. Information sent over the internet without encryption can be seen by other people while it is in transit."

Depending on your browser, you might be able to right-click on part of the page and get security details for that area. A lot of sites encrypt only a small frame containing the password/card details/whatever, or alternatively encrypt most of the page but leave an unencrypted area for adverts. Personally I wish they would do all or nothing as it makes it much easier to be sure.

The encrypted parts should be just as secure as if the whole page was encrypted. The fact that there's less to decrypt may be an advantage to some potential crackers, but then again having less information can make codebreaking harder.

Thanks for your reaction Pastychomper. I agree with you to a point, namely, we don't know which parts of the page are encrypted. We assume or hope that the vital parts ie bank details, are encrypted but we don't know.
I found some information from Firefox (the browser I use) http://mzl.la/MDvkxK "When an HTTPS page has HTTP content, we call that content “mixed”. The page you are visiting is only partially encrypted and even though it appears to be secure, it isn't."

This would seem to be the case with myfavouritemagazine's subscription page, with a blocked content icon and the warning triangle icon.

Somewhere in the HTTP standards it states that is a page is served over SSL, all content on that page must also be served over SSL.

I suspect that the non-SSL content is from the ad servers, but that should not happen. Try installing Ghostery, if it's available for Firefox - I use it on Chromium, or one of the ad-block extensions to see what it tells you.

"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)

Rest assured all your details are safe with us. All transactions are performed on a secure web server.

All information you provide is encrypted (scrambled) using the industry standard SSL (Secure Socket Layer) technology provided by Verisign. So when you submit an order online, nothing can be read as it travels down the secure line. Your details are then applied to our subscription system, which resides in a completely separate, unlinked area, away from our internet pages."

I pulled the plug on my modem once when I had a familar "blink" of my desktop.
Discovered a snapshot of my screen in /tmp. There was nothing all the private, so
when the modem resynced, the snapshot was gone. YEAH, I'd be very careful.